Coated metallic-arc weldrod and method of making the same



April 8, 1930. R. STRESAU 1,754,063

COATED METALLIC ARC WELDROD AND METHOD OF MAKING THE SAME Filed March 12, 1925 INI/"ENTOR.

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Patented Apr. 8, 1930 NITED STATES PATENT OFFICE RICHARD STBESAU, OF 'WAUWATOSA, WISCONSIN, ASSIGNOR TO A. 0. SMITH CORPORA- TION, OF MILWAUKEE, WISCONSIN, A CORPORATION OF NEW YORK COATED METALLIC-ARC WELDROIO AND METHOD O1 MAKING THE SAME Application filed March 12, 1925. Serial No. 14,939.

The invention relates to weldrods of the metallic-arc type, and it resides in a construction in which a metallic wire is provided with a combustible coating or covering containing finely comminuted cellulose flour which is mechanically produced and which will be vaporized by the heat of the arc and thereby produce gases which surround the arc and protect the weld metal being deposited from oxidation and contamination. The various features of the invention will become apparent by reference to the accompanying drawings which illustrate the preferred embodiment of the invention and in which:

Figure 1 is a view in elevation of a weldrod formed as a metallic wire provided with a coating orf-covering of cellulose flour in accordance with the purposes of my invention, the weldrod being broken out at its middle.

. Fig. 2 is an enlarged transverse sectional view on the line 2-2, Fig. 1.

Fig: 3 is an enlarged view in elevation of a short intermediate section of the weldrod with the covering or coating broken away at one side.

Referring to the drawing, the numeral 10 indicates a length of wire which forms the metallic core of my improved weldrod.

This wire constitutes an electrode, and during the welding operation an electric arc is established and maintained between the work to be welded and the wire, and by means of the are thus formed the metal of the wire is progressively deposited through the arc and upon the work.

I apply to the wire 10 a compounded coating or covering 11, while the material forming the latter is in a plastic state, one of the purposes of such covering or coating being to associate with the wire a slowly disintegrating sleeve-like gas retaining envelope, so that a crater will be formed by the unconsumed portion thereof which extends a short distance beyond the end or point of the wire 10 at the time of its progressive fusion, and from which the molten metal flowing from the wire is projected in the form of a metallic vapor upon and into the line of the Weld. The cellulose material used in forming the body of the coating or covering 11 is mixed with silicate of soda, preferably in the proportion of two parts of silicate of soda to five parts of cellulose flour by volume, the properties of the silicate of soda having the effect of preventing too rapid combustion of the cellulose element of the compound, andso permit the formation of the crater always a little in front of the receding point of the progressively fusing wire 10.

As a base for the plastic compound, I use mechanically ground or finely comminuted flour in a powdered form produced from hard wood, non-resinous soft Wood, wheat,v

rye, or the straw of the two latter, or other suitable materials of like nature. Such flour, without undergoing other preparatory treatment, is then mixed with a suitable quantity of silicate of soda so as to produce a stifi', plastic mass of such consistency that it can be made to flow under pressure as desired, and will retain the shape imparted to it by the pressure exerted upon the mass.

The flour produced from Wood, commonly referred to as wood flour or sawdust, and the material produced from the wheat or rye straw may be properly defined as granular comminuted cellulosic material, while the wheat and rye flour are essentially starchy materials. All of the materials mentioned above belong to the same generic class of carbo-hydrate compounds. Such finely comminuted materials may be used separately or in suitable mixtures as a base for the plastic compound.

The coating or covering is applied to the wires by passing the latter through an orifice in a stuft' chest containing the plastic mass, upon which suitable pressure is exerted to cause it to flow with the movement of the wire and form the envelo e about the wire.

The coated or covere weldrods, when dried or baked to substantially free them from moisture and harden the coating or covering, are ready for use. They may, however, be given afinal outer coating of sodium silicate, which latter may be app ied by dlpping or otherwise either before or after the drying operation.

In order to improve the character of the welded joint, I may alloy the wire core of the weldrod with metal of a different nature. The said metal in any suitable form may be applied to the wire and enclosed by the coating or covering, or be alloyed in the wire. Or such metallic element in powdered form may be incorporated in the plastic mixture at the time of its preparation, or in the form of metal strips may be laid in the welding groove and fused into the joint. Such meta may be nickel, manganese, chromium, or any other metal possessing the properties desired, or their oxides. In some instances, I may mix into the plastic a small portion of kaolin, or other material, which will act as a dilutant to reduce the amount of gas generated in the distillation of the materials forming the cellulose and silicate coating or covering of the wire.

In the vaporization and decomposition of the covering material whichtakes place during the welding operation, the cellulosic constituent of the covering produces gases which surround the arc and protect the metal being projected therethrough from oxidation and contamination, and the crater above referred to is formed from the residue which is chiefly carbon. I have found that this carbon rim or crater formation and the metal rod or core provide a combined carbon and metallic ments are present. This is evidenced by the high voltage across the arc, varying from 35 to 48, and the consequent higher temperature, and stability of the are which it is possible to (inainta-in while using the improved weldro In the vaporization and decomposition of the coating or covering, the vapors of the metallic'arc are more effectivel surrounded and protected by the vapors of t e carbon arc,

and a very strong reducing action is present. The gases produced by vaporization extend to and cover the molten area behind the arc. This thorough protection of the are as well as of the molten area around the arc, permits an increased consumption of energy and consequently an increased melting rate, without the absorption of oxygen or nitrogen in the welded joint.

The silicate of soda is a combustion retarder and acts to prevent premature decomposition of the covering materials.

The comminuted carbo-hydrate or cellulosic materials such as hereinbefore specified, of which I prefer to use wood flour or sawdust, when mixed with sodium silicate which acts as a binder and combustion retarding material provides a weldrod coating that is hard and essentially non-porous and-which" retains the gases produced by the gasification of the covermg for liberation at the arc.

I do not, however, limit myself to any particular degree of hardness or non-porosity for the covering malerial, as. the advantages of the invention may be realized while permitting considerable variation in these characteristics of the finished covering.

I have not in this application made specific claims to a weldrod coating formed of starchy material, having claimed the same in a separate application Serial No. 356,182, filed April 18, 1929.

Nor have I in this application made any claims to the use of kaolin as an ingredient of the covering compound, having claimed the same in a separate application filled as a division hereof.

Therrecital herein of specific ingredients and definite proportions of ingredients for 'the weldrod is not intended to exclude the employment of like substances of similar properties and of varying proportions of in gredients within the scope of the invention as expressed in the claims hereinafter.

Having thus described my invention, what I claim and desire to secure'by Letters Patent of the United States, is:

1. A metallic-arc weldrod comprising a metal rod provided with a covering containing a cellulosic flour.

2. A metallic-arc weldrod comprising a metal rod rovided with a covering containing carboydrate flour and a binder there arc 1n which the characterlstlcs of both elef 3. A metallic-arc weldrod constituted as a metal rod rovided with a covering containing carboydrate flour and an ingredient which retards combustion of said flour.

4. A metal are weldrod constituted as a metal rod having formed thereon a coverin of finely comminuted cellulose material, sai cellulose material having mixed therewith a binding and combustionretarding material.

5. A welding electrode comprising a metal rod of suitable shape, said rod being provided with an adherent coating containing as a constituent thereof comminuted carbohydrate material.

6. A welding electrode comprising a metal rod of suitable shape, said rod being provided with a coating containing as a constituent thereof comminuted cellulosic material in the form of sawdust.

7. A welding electrode comprising a metal rod of suitable shape, provided with a coating conferring desirable we ding characteristics upon said electrode, said coating containing sawdust as a constituent thereon.

8. A welding electrode comprising a metal rod of suitable shape, said rod being provided with an adherent coating containing as a constituent thereof granular comminuted cellulosic material.

9. An electrode for use in arc welding comprising a metal rod of suitable shape provided with a coating conferring desirable Welding characteristics upon said electrode, said coating comprising suitable fiuxing ingredients, granular comminuted cellulosic material, and a binder of sodium silicate.

10. A metallic-arc weldrod constituted as a metallic wire provided with a hardened, nonporous, gas-retaining coating or covering of cellulose flour and a binder therefor.

11. A metallic-arc weldrod constituted as a metallic wire provided with a gas-retaining coating or covering formed of cellulose flour and silicate of soda.

12. A metallic-arc weldrod constituted as a metallic wire provided with a gas-retaining coating or covering of wood flour mixed with silicate of soda.

13. A metallic-arc weldrod constituted as a metallic wire provided with a hardened, nonporous, gas-retaining coating or covering containing carbo-hydrate flour and having properties to create in the fusion of the weldrod a protecting carbon are about the metallic arc and a protecting gas about the welded area.

14. A metallic-arc weldrod constituted as a metallic wire having formed thereon a gasretaining coating or covering of finely comminuted cellulose flour, and having mixed therewith a heat resisting substance as a binder, in combination with a metal of difierent characteristics for alloying the welded oint.

15. The process of preparing covered weldrods for arc welding, which comprises the mixing of finely powdered cellulose flour with silicate of soda into a plastic mass, and applying a coating of the latter to a welding wire to constitute a gas-retainingcovering for the wire.

16. The process of preparing coated weldrods for metallic-arc welding, which comprises the preparation of a quantity of finely comminuted wood flour, mixing silicate of soda therewith to form a plastic, applying a coating-of the latter to the wire core of the weldrod, and drying the same to constitute a gas-retaining coveringfor the wire.

17. The process of preparing covered weldrods for arc welding, which comprises the preparation of finely divided cellulose flour, mixing the flour with silicate of soda into a plastic mass, applying a coating of the latter to a Welding Wire, drying the same to constitute a gas-retaining covering for the wire, and applying an additional coating of R. STRESAU. 

